I would have been better to link to this 20 February radio interview with the scholar at the centre of the controversy, Daniel Wallace, which gives some more details - though not really much more - of the find: this is a manuscript which came from Egypt somehow, and has so far been dated by one unidentified but apparently well-regarded palaeography expert to the first century.(The radio host makes the puzzling remark that "it can't be later than 51", which cannot be correct; Wallace does not either confirm or correct the remark.) Mutterings elsewhere indicate that it may (or may not) be part of the Green Collection, possibly a papyrus fragment from a late Egyptian mummy.
Tracking through internet discussion of this, I have become rather depressed by the poor quality of the debate between liberal and evangelical theologians. The evangelicals seem delighted by the idea that this discovery - if it is true - will push back the known fragments of manuscript to within the lifetime of the apostles, and may (or may not) indicate that the specific fragment of text on it has (or has not) remained unchanged since the earliest days. The liberals, on the other hand, have been mocking the evangelicals for a fake manuscript that isn't even the piece in question.
Myself, I've done a wee bit of New Testament Greek and scriptural analysis, and I've done a wee bit more palaeography and attempts to reconstruct original texts (of a much later date) from various manuscript versions, enough altogether to make me feel that both the evangelicals and the liberals who I've read on this particular topic seem to me to be approaching it with too many preconceptions. If we do have a genuine first century manuscript, that should be a cause for general celebration, full stop. Scholars will certainly continue to debate what it means and how significant it is, but a couple of verses of Mark's gospel in a fragment of a first-century manuscript can't and won't ever prove that the entire New Testament reached its present form by AD 70.
(Though at least none of the people I have read on this question are King James-ers.)